1. Field of the Invention
Apparatuses consistent with the present invention relate to a perpendicular magnetic recording head, and more particularly, to a perpendicular magnetic recording head including a gap shield formed between a main pole and a return pole to improve the field profile of the perpendicular magnetic recording head, and a perpendicular magnetic recording apparatus including the same.
2. Description of the Related Art
With the advent of the Information Age, the amount of information that a person or an organization deals with has significantly increased. For example, many users employ computers having high data processing speed and large information storage capacity to access the Internet and obtain various pieces of information. CPU chips and computer peripheral units have been developed to enhance the computer data processing speed, and various types of high density information storage media like hard disks are being researched to enhance the data storage of computers.
Recently, various types of recording media have been introduced. Most of the recording media use a magnetic layer as a data recording layer. Data recording of a magnetic recording media can be classified into longitudinal magnetic recording and perpendicular magnetic recording.
In the longitudinal magnetic recording, data is recorded using the parallel alignment of the magnetization of the magnetic layer on a surface of the magnetic layer. In the perpendicular magnetic recording, data is recorded using the perpendicular alignment of the (magnetization) on a surface of the magnetic layer. From the perspective of data recording density, the perpendicular magnetic recording is more advantageous than the longitudinal magnetic recording
FIG. 1A illustrates a conventional perpendicular magnetic recording apparatus. Referring to FIG. 1A, the conventional magnetic recording apparatus includes a recording medium 10, a writing magnetic head 30 recording data on the recording medium 10, and a reading magnetic head 20 reading the data of the recording medium 10. The writing magnetic head 30 includes a sub yoke 21 and a intermediate layer 50. The reading magnetic head 20 includes first and second magnetic shield layers S1 and S2, and a reading magnetoresistance device 31 is interposed between the first and second magnetic shield layers S1 and S2. When data is being read from a predetermined position of a selected track, the first and second magnetic shield layers S1 and S2 shield the magnetic field generated by magnetic elements around the predetermined position from reaching the predetermined position on the track. The reading magnetoresistance device 31 may be a giant magnetoresistance (GMR) or a tunnel magnetoresistance (TMR). In FIG. 1A “X” denotes a track direction “Y” denotes a cross direction, and “Z” denotes a direction perpendicular to both X and Y.
FIG. 1B is an extended view of portion A of the magnetic recording apparatus shown in FIG. 1A. The magnetic recording apparatus includes a main pole P1 of the writing magnetic head 30, a return pole P2 separated from the main pole P1, and an induction coil generating a magnetic field to the main pole P1. The quality of signals input to the recording medium 10 depends on the writing magnetic head 30, and particularly, on magnetic features of the main pole P1 and the second return pole P2. As recording density of recording devices increases, the bit size of the recording medium 10 becomes smaller. Accordingly, the magnetic material used for the main pole P1 and the return pole P2 needs to have a great saturated magnetization value, great permeability, and a soft magnetic characteristic with small coercivity. In FIG. 1B, “G” denotes a gap between the main pole P1 and the return pole P2.
When recording data on the recording medium 10, the magnetic field generated by the main pole P1 of the writing magnetic head 30 magnetizes a recording layer of the recording medium 10 in a predetermined direction, and returns to the return pole P2. The perpendicular magnetic recording head moves in the direction of the track of the recording medium 10 and records data. Preferably, the data is recorded inside the track. However, it is difficult to control the magnetic field emitted from the main pole P1, and a recording layer of an area outside the track, that is, an off track area is affected. This deteriorates the recording characteristic.
FIGS. 2A and 2C illustrate a structure of a perpendicular magnetic recording head in which side shields SS are formed on both sides of the main pole P1 for reducing the above described spray field effect. FIG. 2A illustrates a lateral side of the main pole P1 and a lateral side of the return pole P2. FIG. 2B is a front view of the main pole P1 and the return pole P2. FIG. 2C is a cross-sectional view of an air bearing surface (ABS) seen from the magnetic recording medium in the direction of the recording magnetic head 30. Referring to FIGS. 2A through 2C, side shields SS reduce the influence of the magnetic field emitted from the main pole P1 on the off track area of the magnetic recording medium. However, when a shield is simply formed, the strength of the perpendicular magnetic field for recording data in the perpendicular magnetic medium is reduced. Thus, a shield structure that is optimized to effectively control the magnetic field profile is required.